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A Petry

Publications and source records attributed to A Petry.

17 recordsLinked to original sources
PubMed2002

The use of a bronchial blocker compared with a double-lumen tube for single-lung ventilation during minimally invasive direct coronary artery bypass surgery.

OBJECTIVE: To investigate whether a bronchial blocker (BB) placed through a routinely used single-lumen tube (SLT) to achieve 1-lung ventilation is appropriate in patients undergoing a minimally invasive direct coronary artery bypass (MIDCAB) operation. DESIGN: Clinical trial. SETTING: University hospital. PARTICIPANTS: Patients scheduled for elective MIDCAB operation (n = 159). INTERVENTIONS: Group A was treated with a left-sided double-lumen tube (DLT) and served as the control group. Group B was intubated with a routinely used SLT in combination with a BB. MEASUREMENTS AND MAIN RESULTS: The following data were collected: (1) time required for placement of each tube, (2) ventilation pressures, (3) lung compliance, (4) dislocations of the DLT or BB, (5) effectiveness of lung collapse, and (6) PaO(2) and fraction of inspired oxygen. In 4 patients (4%) of group B, the BB could not be placed within an acceptable time so that 155 patients (50 patients in group A, 105 patients in group B) were statistically analyzed. Statistically significant differences during 1-lung ventilation were found for peak and mean inspiratory pressure (p < 0.001 and p < 0.05), dynamic and static lung compliance (p < 0.05), and dynamic lung compliance change (p < 0.01). No statistical significance was found for intubation time (p > 0.05) and PaO(2) and fraction of inspired oxygen (p > 0.05). Lung collapse was insufficient in 1 patient of group A (2%) and in 2 patients of group B (2%). CONCLUSION: To achieve 1-lung ventilation during a MIDCAB procedure, the use of a BB combined with an SLT is an appropriate technique as an alternative to the commonly used DLT.

Aged↗
PubMed2001

Dose-response relationship of propofol on mid-latency auditory evoked potentials (MLAEP) in cardiac surgery.

BACKGROUND: Propofol-sufentanil anaesthesia has become popular during cardiac surgery for its titrability and short recovery time. Avoidance of awareness is a major goal during cardiac surgery. We therefore investigated the dose-response relationship of propofol and cortical responses (mid-latency auditory evoked potentials, MLAEP). METHODS: One hundred patients undergoing cardiac surgery were investigated. Basic anaesthesia was performed with sufentanil (4.5 microg kg(-1) h(-1)) / flunitrazepam (9 microg kg(-1) h(-1)) infusion (control group); the other groups received in addition a loading dose of propofol 2 mg kg(-1) and a maintainance infusion of 1-3.5 mg kg(-1) h(-1). MLAEP were evaluated by using Pa/Nb-amplitudes and Nb-latencies. Haemodynamics were monitored by ECG, arterial blood pressure and cardiac function with pulmonary artery catheterization. RESULTS: In the control group, median amplitude of MLAEP decreased by 50% with a wide range, but were detectable in >90% of patients throughout surgery. Propofol suppressed amplitude Pa/Nb of MLAEP dose dependently. With 3.5 mg kg(-1) h(-1) amplitudes disappeared in >40% of patients throughout cardiac surgery. Median Nb-latencies increased in the control group from 44 to a range from 50 to 60 ms. In groups with propofol >2 mg kg(-1) h(-1), Nb-latencies, detectable in the patients without complete suppression of MLAEP, increased to median 60 ms. Haemodynamic parameters and cardiac function did not differ among the groups. The use of vasopressors was not increased even with the highest propofol dose used. CONCLUSION: The dose-response effect of propofol on auditory evoked potentials reveals that combining a loading dose of 2 mg kg-1 with a consecutive infusion of 3.5 mg kg(-1) h(-1) significantly suppresses MLAEP during cardiac surgery. Thus, auditory information may not be processed and awareness with recall becomes unlikely.

Adolescent↗
PubMed2001

[Robotic surgery--surgical and anesthesiologic implications].

Because of the restricted freedom of movement inherent in endoscopic standard instruments wholly endoscopic heart surgery has not been possible up to now. The development of such techniques was especially hindered by the rib cage. Now the precision which is imperative for bypass surgery or valve reconstruction is made possible by telemanipulator systems. Preconditions for this method are cardiopulmonary bypass-techniques which allow a cardioplegic cardiac arrest with closed chest and extensive hemodynamic monitoring which enables the anesthesiologist to make exact diagnoses without having a direct view on the heart. After an extensive experimental phase a telemanipulation system is successfully in use since May 1998 in the Cardiac Center in Leipzig.

Anesthesia↗
PubMed1998

Computer aided monitor-data processing (CAMP). A landmark for unbiased gauging of anaesthetic courses?

UNLABELLED: A computer aided monitor-data processing system (CAMP-System) was developed in order to get a consistent and comprehensive database which can very precisely reflect intra-operative haemodynamic courses. The goal of the present study was to introduce a new method to scan and to gauge haemodynamic courses and to demonstrate its superiority over the traditional way of data processing based on a handwritten anaesthesia protocol. METHODS: The computerized system was applied to a study which was designed to investigate the influence of ketanserin (K) vs. urapidil (U) on haemodynamic stability during cardiac operations. Twenty male patients scheduled for myocardial revascularization received either 20 mg K or 30 mg U. Heart rate, central venous, arterial and pulmonary artery pressures were measured and on-line recorded every 20 seconds by the computer record system. In the handwritten protocol these variables were registered at eight pre-defined time points. Computerized data processing (including artifact depletion and data condensation) was compared to the results evaluated from the handwritten protocol. RESULTS: While the only significant differences in the handwritten protocol were slightly higher values of pulmonary artery pressures in group K, the computer analysis revealed a number of further differences. Higher maximum and a less stable time course of HR in group K in the pre-bypass phase and lower mean and standard deviation of MAP during cardiopulmonary bypass. CONCLUSION: Computerized data processing including automatic artifact suppression and data condensation was able to reveal differences in the course of haemodynamic variables that cannot be detected in a conventional handwritten protocol.

Adrenergic alpha-Antagonists↗
PubMed1998

Intraoperative monitoring with somatosensory evoked potentials in carotid artery surgery--less reliable in patients with preoperative neurologic deficiency?

BACKGROUND: In a retrospective analysis of intraoperative somatosensory evoked potential (SEP) results during carotid artery surgery we found some cases with postoperative neurologic deficits, surprisingly without significant SEP changes. METHODS: Median nerve SEP were monitored as usual. Indication for selective shunting was a complete loss of amplitude N20/P25 in the first period of the investigation, later on a 50% reduction, or a prolongation of the central conduction time (CCT) of about 1.5 ms after cross-clamping. Anaesthesia was maintained with isoflurane in N2O/O2, fentanyl and atracurium. RESULTS: Over a 3-year period 146 patients were monitored. Indications were: transient ischaemic attacks (TIA) (n=51), stroke (n=23), stroke with residuals (n=39), asymptomatical stenosis (n=29), subclavian steal syndrome (n=4). Twenty-four patients received an intraluminal shunt following SEP alterations. Postoperatively, 5 patients (3.4%) had symptoms of intraoperative brain ischaemia (stroke n=2, TIA n=3), 4 of them showing only minor intraoperative SEP alterations; 1 received a shunt because of CCT prolongation. Four of these 5 patients had cerebral neurologic deficiency preoperatively. CONCLUSION: Since some authors have found a 100% sensitivity of intraoperative SEP, it is remarkable, that 1 patient with postoperative stroke and 3 patients with TIA had no significant SEP changes intraoperatively. We suppose there was an association with preoperative neurological deficits resulting from previous strokes. In such cases, regional critical ischaemia may apparently occur outside the sensory pathway monitored with SEP.

Aged↗
PubMed1996

Effects of enoximone on right-ventricular function in patients with impaired myocardial performance.

The effects of an enoximone monotherapy on left-ventricular and especially on right-ventricular haemodynamics were investigated in fourteen patients with impaired left-ventricular function secondary to coronary artery disease. Anaesthesia was induced and maintained with fentanyl and flunitrazepam. After reaching steady state, a bolus of 0.5 mg/kg enoximone was administered, followed by an infusion of 0.5 microgram/kg/min. Besides the common haemodynamic parameters particulary the right-ventricular ejection fraction (RVEF) was measured using a special thermodilution technique. The predefined time points were: before administration of enoximone (baseline) and 5 min, 10 min, 15 min, 20 min, and 30 min after bolus injection of enoximone. Compared to the baseline the maximum effects of enoximone were a 28% increase of cardiac index accompanied by a 39% decline of systemic vascular resistance and an unchanged left-ventricular stroke-work index. While central venous pressure and mean pulmonary artery pressure remained unchanged. RVEF (+20%) and right-ventricular stroke-work index (+30%) were significantly augmented, augmented, indicating improved right-ventricular performance. No adverse effects of the enoximone administration were observed perioperatively. We conclude that an enoximone monotherapy is beneficial for patients with impaired myocardial function undergoing cardiac surgery.

Adult↗
PubMed1995

[Online recording of monitor data. The artifact problem].

Increasing numbers of monitors at the anaesthesiologist's workplace, providing more than 20 different parameters of the patient's condition, have already made it impossible to record all the values in a handwritten form. Consequently, this most common method of record-keeping must be incomplete and inaccurate. In recent years computerised data-acquisition systems have been introduced into clinical practice in order to produce more reliable records. But after a 7-year experience in the use of such a system in cardiac anaesthesia, we have recognised certain problems that remain to be solved before automated record-keeping will achieve wider acceptance. The first is the handling problem, which was discussed in a previous paper. The second major problem is the appearance of artifacts, caused mainly by mechanical manipulations during the operation. In this paper, 300 courses of anaesthesia that were recorded online during different cardiac surgery procedures were examined and the incidence as well as the kind of artifacts occurring were evaluated. Algorithms were developed for each haemodynamic parameter to suppress these artifacts automatically by a subsequent analysing process; the efficiency of that "artifact filter" was validated in 35 of the 300 cases. Based on more than 30,000 values for each parameter, the incidence of artifacts was 3%-7%. However, only 0.1%-0.5% of the artifacts could not be eliminated by the filter. The method described here provided acceptable graphic printouts of the most important haemodynamic parameters (Figs. 1b and 2b) and would also be suitable to serve as an input filter for automatically running anaesthesia data-examination processes, which are currently being developed in our clinic.

Adult↗
PubMed1995

The influence of ketanserin or urapidil on haemodynamics, stress response and kidney function during operations for myocardial revascularisation.

The study was performed to investigate the different effects of ketanserin and urapidil on haemodynamics, kidney function and plasma catecholamine and aldosterone levels. Forty male patients scheduled for myocardial revascularisation were assigned at random to two groups: group K received ketanserin, group U received urapidil. Anaesthesia consisted of fentanyl, flunitrazepam and pancuronium. Haemodynamic variables were evaluated at eight predefined time points of the operation. Creatinine and free-water clearance as well as plasma levels of adrenaline, noradrenaline and aldosterone were measured in three different periods of the operation. While the groups showed no clinically relevant differences in the haemodynamic variables and the hormone plasma concentrations, the creatinine clearance in group K was slightly increased in the period after cardiopulmonary bypass. Both ketanserin and urapidil prevented hypertension even in the presence of elevated catecholamine plasma levels during and after cardiopulmonary bypass.

Adrenergic alpha-Antagonists↗
PubMed1994

Effects of amrinone on left and right ventricular function in patients with impaired myocardial performance during general anaesthesia.

We have studied the effects of amrinone on left and right ventricular haemodynamics in patients with impaired ventricular performance caused by coronary artery disease. Anaesthesia was achieved with fentanyl, flunitrazepam and pancuronium. After reaching steady state, a bolus dose of amrinone 0.5 mg kg-1 was administered followed by an infusion of 1 mg kg-1 h-1. Right ventricular ejection fraction (RVEF) and other haemodynamic variables were evaluated at six times: before, 5, 10, 15, 20 and 30 min after bolus administration of amrinone. Amrinone led to a 23% increase in cardiac index resulting mainly from reduction in afterload. While central venous pressure and mean pulmonary artery pressure remained unchanged, RVEF increased by 28%. This effect may be interpreted as an improvement in right ventricular performance.

Adult↗
PubMed1994

Bicaval versus atrial anastomoses in cardiac transplantation. Right atrial dimension and tricuspid valve function at rest and during exercise up to thirty-six months after transplantation.

Conventional cardiac transplantation with atrial anastomoses alters atrial integrity, geometry, and possibly function. Theoretically, this may also contribute to the development of tricuspid insufficiency that is frequently observed after the operation. Thus more anatomic transplantation techniques using bicaval anastomoses were recently introduced into clinical practice. Knowledge of their efficacy, however, is scarce. Therefore right atrial size and tricuspid valve function were compared in patients with bicaval (group A) and standard atrial (group B) anastomoses in a randomized, prospective study. The results of this echocardiographic study at rest and exercise in 18 patients (bicaval n = 8; atrial n = 10) on the average 28 months after transplantation are presented. The right atrial dimension was comparable between group A patients and control subjects and larger in group B patients (p < 0.05). The incidence of tricuspid regurgitation was not different between the two groups at rest, but it was at exercise (50 watts of workload) (p < 0.05). This study suggests that up to 36 months after cardiac transplantation the technique of bicaval in contrast to atrial anastomoses preserves right atrial size and reduces tricuspid regurgitation during exercise. Whether this leads to improved hemodynamics and increased exercise capacity remains to be evaluated in a larger series of patients.

Cardiac Output, Low↗
PubMed1993

[Potassium substitution during coronary surgery: K(+)-Mg+(+)-aspartate-complex (Inzolen) versus potassium chloride].

Potassium loss may cause arrhythmias and cardiac injury in patients undergoing heart surgery with cardiopulmonary bypass (CPB). In a prospective, randomized trial two different methods of potassium substitution were investigated regarding their influence on cardiac rhythm following reperfusion. Patients received either potassium chloride (Group I, n = 102) or potassium magnesium aspartate (Inzolen, group II, n = 105) to achieve intraoperative serum potassium concentrations of 4.5 mmol/l. St. Thomas cardioplegic solution was used. CPB was performed in moderate hypothermia (28-32 degrees C) with a non-pulsatile pump flow, a membrane oxygenator and a single two-stage venous catheter. The two study groups were comparable with regard to biometric data, preoperative state, duration of operation, ischemia and clinical outcome. In 6 patients in group I and in 3 patients in group II perioperative myocardial infarction was diagnosed based on ECG and CK-MB findings. One patient in each group died during the postoperative hospital stay. At the time of declamping mean serum potassium concentration was 4.9 +/- 0.7 mmol/l in group I and 4.8 +/- 0.5 mmol/l in group II (n.s.). The concentration of magnesium was significantly lower in the potassium chloride substitution group (1.48 mmol/l) compared to the other group (2.33 mmol/l) (p < 0.05). No significant differences in cardiac electric activity were observed between the two groups. The incidence of ventricular fibrillation in the early reperfusion period was 37% versus 45% (n. s.). In both groups patients with a potassium value of < 4.5 mmol/l showed a significantly higher incidence of ventricular fibrillation. Five percent of the patients had bradycardia requiring temporary pacing.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspartic Acid↗
PubMed1993

[The potential dependence of the effect of bupivacaine and ropivacaine on the heart. In-vitro studies on the effect of local anesthetics on the force of contraction and the action potential in left guinea pig atria].

The cardiotoxicity of long acting local anaesthetics is still a matter of controversy. Therefore, the effects of bupivacaine and ropivacaine on cardiac contractility and electrophysiologic parameters were evaluated in the presence of different extracellular potassium concentrations. METHODS. In strips from left atria of guinea pigs action potentials were induced to obtain cumulative dose response curves for bupivacaine (racemic mixture) and ropivacaine (S-enantiomer). Effects on force of contraction and parameters of the action potential (especially maximum upstroke velocity, dV/dtmax, as an indirect measure of fast sodium channel function) were compared for low (2.7 mM) and high (8.7 mM) extracellular K+ concentrations (n = 7-8). RESULTS. At low K+ concentration, bupivacaine and ropivacaine depressed force of contraction and dV/dtmax in a dose-dependent manner. At higher local anaesthetic concentrations, action potential amplitude decreased and action potential duration was prolonged. There was no influence on the resting membrane potential (Tables 2, 3). At high K+ concentration, both local anaesthetics induced effects similar to those observed with low K+, but the dose-response curves for contractility and dV/dtmax were shifted leftward. The EC50 of bupivacaine for the negative inotropic effect and, analogously, for dV/dtmax was approximately 10 times lower. Similar results were observed for ropivacaine (Figs. 1, 2). CONCLUSION. This study confirms the dependence of the cardiodepressive effects of bupivacaine on the extracellular K+ concentration (i.e. membrane potential). The present investigation shows a similar dependence for the effects of ropivacaine, a new long-lasting local anaesthetic. Our results concerning the potential dependency of dV/dtmax depression are compatible with the binding of bupivacaine to the inactivated state of the sodium channel protein preferentially (modulated receptor hypothesis). Thus accumulation of block will occur if stimulation frequency is in an appropriate range. Though we found striking analogies between potential dependency of dV/dtmax depression and negative inotropic effect, there is no firm evidence that the sodium channel block by bupivacaine or ropivacaine substantially participates in the latter effect. An influence on other ionic channels such as the calcium channel remains to be evaluated.

Action Potentials↗
PubMed1993

[The neuropathy of the autonomic nervous system. An additional anesthetic risk in diabetes mellitus].

Some 20-40% of diabetics suffer from an autonomic neuropathy. This complication of diabetes mellitus impairs the regulation and the reflexes of the cardiovascular system. This study compares the cardiovascular characteristics of diabetics and nondiabetic control patients. METHODS. 21 patients (11 diabetics, 10 nondiabetics) undergoing ophthalmic surgery were investigated. They were tested preoperatively for autonomic cardiovascular dysfunction by application of four established tests. These were: heart rate responses to the Valsalva maneuver, deep breathing and standing up (30/15 test) and the Schellong test. The anaesthesia was induced with fentanyl (0.1 mg), etomidate (2.5 mg/kg) and succinyl choline (1.5 mg) and maintained with oxygen/nitrous oxide (1.4:3 l/min) and isoflurane (0.2-0.8 vol%). Blood pressure and heart rate were automatically measured every minute during induction of anaesthesia and every 3 min during anaesthesia. Additionally the heart rate response to 0.5 mg atropine i.v. was evaluated. RESULTS. The autonomic function tests revealed pathologic reactions in all diabetics (two early, six definitive, three severe) and none in controls. Remarkable cardiovascular events occurred exclusively in the diabetic group, especially during induction of anaesthesia. The systolic blood pressure (SAP) increased in diabetics from a preinduction value of 150 mmHg (median, range 105-205 mmHg) to a maximum of 200 mmHg (160-250 mmHg) after intubation, in controls from 130 (100-150 mmHg) to 170 (110-190 mmHg). Following this peak, SAP fell in diabetics to 120 mmHg (80-160 mmHg), in controls to 110 (100-140 mmHg). Two diabetics had to be treated because of an SAP exceeding 220 mmHg, two other diabetics because of an SAP below 80 mmHg. After atropine administration the heart rate of diabetics showed a median increase of 15% (range 0-40%). In four diabetics, however, the increase was less than 10%. In control patients the increase was 50% (40-80%). All patients with severe cardiovascular reactions during induction of anaesthesia and with heart rate elevation following atropine of less than 10% had a definite or severe neuropathy of the autonomic nervous system revealed by the tests. DISCUSSION. In the only slightly stressful ophthalmic surgery, remarkable events were noted particularly during the induction of anaesthesia. The critical decreases and increases of SAP might be related to the autonomic dysfunction, because of the hypersensitivity of a partly damaged autonomic nervous system or its impaired function. This led to a loss of heart rate variation and adequate blood vessel tone. The severe cardiovascular reactions always went along with clearly pathologic findings in the tests performed. Normal test results in diabetics implied normal cardiovascular reactions, as could be observed in nondiabetics. CONCLUSION. Abnormal cardiovascular reactions in diabetics must be kept in mind. The simple tests specified here can identify such predisposed patients.

Adult↗
PubMed1993

[Computer-aided anesthesia monitoring. Experiences with the use of three systems in heart surgery].

Basic monitoring in cardiac anaesthesia embraces at least 19 different parameters of haemodynamics and blood gas analysis. In special cases additional measurements may be desirable, providing a total of up to 44 variables displayed on various monitors, as depicted in Fig. 2. The recording of such an amount of data is only feasible with automated recording systems. Therefore, in the past 6 years we have introduced three different computer systems to our cardiac anaesthesia workplaces. The experiences in their handling are reported. MATERIAL AND METHOD. Three systems were investigated: (1) System S 4000 (Siemens, Germany), based on a central processor unit (PDP 11, DEC, Japan) connected with 20 bedside input/output terminals and Sirecust 404a monitors (Siemens). The system collected the data in a ring buffer with a capacity for about 24-48 h. (2) Patient Care Manager (PCM; Siemens, Germany), a single workplace system based on an IBM-compatible personal computer (PC) with the operating system environment DOS 5.0/Windows 3.0. In our test configuration it was connected with a Sirecust 1281 monitor (Siemens). (3) Monitor-Data-Manager (MDM) (our own development). This single workplace system is also based on an IBM-compatible PC running under DOS and was connected to four different monitors used in our cardiac surgery operating theatre (Fig. 2). A second computer (Sirecust S 425, Siemens) served as an interface between the two 404 monitors (not featuring a serial output like RS 232) and the PC. The self-developed program for that interface was memory resistant and executable with three key presses when the anaesthetic record was started. The three systems were compared with regard to their ease of use, function and practicability. RESULTS. System S 4000: Because of the older system architecture, the response time to key inputs was fairly long and the menu structure somewhat uncomfortable. A major drawback was the limited data buffer capacity and the lack of a long-term storage medium as well as the lack of compatibility with the industry standard for PCs. Software interfaces to other companies' monitors were not implemented, limiting the system to the Sirecust 404 devices. Patient-Care-Manager: The user interface is a Windows 3.0 application representing an up-to-date graphical environment. Unfortunately some Windows features were not fully used, e.g. the free positioning and sizing of graphic windows and the color options. Drug inputs were somewhat long-winded, limiting the system's suitability for the operating theatre. The main disadvantage, however, was the lack of interfaces to monitors other than those from Siemens. Monitor Data Manager: The system was designed to sample data from all monitors operating in our hospital's heart surgery department. Each parameter was displayed in a digital form to get close control over the recorded data (Fig. 1b); additionally calculated values like total peripheral resistance or oxygen demand could be drawn from a separate window. Furthermore, key inputs were reduced to minimum, making drug inputs faster than the hand-written protocol. The ease of performing calculations of continuous drug infusions (from microgram/kg/min to ml/h pump speed) was particularly appreciated by the users. Since the data were saved as an ASCII file, they could easily be imported by any spreadsheet like Lotus 1-2-3 or Excel, providing the whole variety of their graphical presentation or calculation features. Because of the high sampling rate (3 min), even short-lasting drug effects could be registered, making the system favourable for scientific studies. CONCLUSION. Automated monitor data record systems are considered to be a prerequisite not only for research in anaesthesia but also for quality assurance. A basic requirement for wide acceptance in clinical practice is a user interface that provides fast and convenient key inputs as well as further information about parameters not displayed on other monitors. In our h

Anesthesia↗
PubMed1993

Time course of dimension and function of the autologous pulmonary root in the aortic position.

Although the autologous, fully vital, and compatible pulmonary root theoretically offers the prospect of an ideal aortic valve substitute, this type of replacement is performed in only a few centers. Major concern relates to the fate of root dimension and function in the systemic circulation and is largely unknown. To investigate the fate of the aortic root, we conducted echocardiographic examinations of eight freestanding pulmonary roots used for aortic valve replacement in adults. The studies were performed at discharge from the hospital and up to 21 months (mean 12.5 +/- 6.6 months) after the operation, as well as in 26 matched control subjects. There were no significant differences between the first and second postoperative studies regarding the root diameter (mean 26.6 +/- 2.1 mm and 27.6 +/- 2.6 mm, respectively), which was within control limits, the maximum transvalvular pressure gradient (mean 4.6 +/- 1.2 mm Hg and 6.6 +/- 2.1 mm Hg, respectively), the maximum leaflet separation (mean 22.1 +/- 1.4 mm and 22.1 +/- 1.8 mm, respectively), and the degree of insufficiency. At the first study, grade I aortic regurgitation was found in four patients and grade I-II in one patient. Regurgitation increased slightly in one patient with an abnormal leaflet. In three patients primary grade I regurgitation disappeared. These data suggest that the pulmonary root in the aortic position can withstand systemic circulation without changes in dimension and function for up to 21 months. Furthermore, some evidence is provided to indicate that in certain cases the viable autograft may adapt to systemic pressure, as indicated by the disappearance of primary regurgitation.

Aortic Valve Insufficiency↗
PubMed1992

[Nifedipine versus nitroglycerin in aortocoronary bypass surgery. The effect on hemodynamics, kidney function and homologous blood requirement].

Even during adequate general anesthesia, hypertension is a common phenomenon in patients undergoing aortocoronary bypass grafting (CABG). In such cases application of vasodilators is recommended in order to decrease myocardial oxygen consumption. This study was performed to compare two commonly used substances, i.e., nitrates and nifedipine, with regard to their influence on hemodynamics, renal blood flow, kidney function, and the requirement for homologous blood transfusions. METHODS. Forty-four patients gave their informed consent to the study. They were randomly divided into 2 groups: group 1 received nitroglycerin (3.0 micrograms/kg.min), group 2 nifedipine (Adalat, 0.5 microgram/kg.min) in order to prevent hypertension in the phase before onset of cardiopulmonary bypass (CPB). Anesthesia was induced by etomidate and succinylcholine and maintained as a modified neuroleptanalgesia with fentanyl (up to 50 micrograms/kg), midazolam (0.3 mg/kg.h), and pancuronium (0.1 mg/kg). Systolic blood pressure was kept within the range of 120-160 mm Hg; in case of higher values boluses of either 0.25 mg nitroglycerin or 0.5 mg nifedipine were administered. Cardiac index, stroke volume index, rate-pressure product, intrapulmonary shunt, and pulmonary and total peripheral resistances were evaluated at five predefined points: (1) after induction of anesthesia; (2) before incision; (3) before cannulating the aorta; (4) after decannulating the aorta; and (5) at the end of operation. Creatinine and free-water clearances as well as sodium and potassium excretion were calculated for three phases of the operation: (A) induction of anesthesia--onset of CPB; (B) during CPB; and (C) end of CPB--end of operation. CPB was performed using a membrane oxygenator (Sorin 51) and a nonpulsatile blood flow of 2.5 1/min.m2, which was reduced during mild hypothermia of 30-32 degrees C to 1.7 l/min.m2. Mean arterial pressure in both groups was kept at approximately 70 mm Hg. In case of lower pressures norepinephrine (50-100 micrograms/bolus) was administered; higher pressures were treated as described above. Volume substitution was performed initially by 500 ml hydroxyethyl starch and continued, if necessary, by homologous blood or 5% human albumin in order to keep the hematocrit greater than 30 in the phases before and after CPB. RESULTS. Group 2 showed significantly higher values of cardiac index and stroke volume index at point 3 while the rate-pressure product was clearly lower, indicating better myocardial performance and lower oxygen consumption than in group 1. Creatinine and free-water clearances in all three phases did not differ. However, sodium excretion during CPB was significantly higher in the nifedipine group while potassium excretion showed no differences. The average requirement for blood and blood substitutes was lower in group 2, but the difference could not be confirmed statistically because of the large dispersion of values. Nevertheless, 4 patients in the nifedipine group but no patient in group 1 did not need homologous blood transfusion. CONCLUSION. In comparison to nitrates, nifedipine showed some advantages in the treatment of hypertension during CABG: (1) it provided better myocardial performance; (2) it had a more reliable but not too long-lasting effect on elevated total peripherial resistance, leading to better hemodynamic stability; and (3) by not affecting the capacitance vessels it may necessitate fewer homologous blood transfusions.

Adult↗